Decision revisions modulated by synaptic inhibition in the olfactory bulb facilitate learning

Abstract

Behavioral responses are preceded by decisions based on perceived sensory evidence. In real life, sensory inputs are often noisy and change incessantly, raising the question of when and how accurate decisions are made. Cognitive flexibility allows us to revise the choices in case of perceptual conflicts, leading to response revisions. This involves switching between available choices or rapidly stopping misconstrued responses. Here, we quantified these erroneous behavioral actions and studied the underlying neural mechanisms. Mice were trained on an olfactory decision-making task wherein they had to distinguish between a rewarded and an unrewarded stimulus by responding with a lick or withholding it. While the animals respond by licking for both rewarded and unrewarded odor stimuli at the initial stages of learning, the responses almost disappear for the unrewarded ones in the learned stage. However, animals tend to initiate lick responses and stop within a few milliseconds for a few unrewarded trials, even when accuracy levels are high. We describe this phenomenon as decision revisions (DR), and observed it in 5-25% of trials among high-performance blocks. These revisions were mostly observed within a few hundred milliseconds of stimulation. We observed a significantly higher number of revision trials for binary odor mixture discriminations compared to monomolecular ones. Further, by enhancing inhibitory synaptic signaling in the olfactory bulb through photoactivation of ChR2-expressing GAD65-positive GABAergic interneurons, we observed faster odor discrimination and fewer revision trials. Thus, our findings confirm decision revisions that are stimulus complexity-dependent and the pre-cortical control over such a complex cognitive activity. Highlights of the studyO_LIMice revise context-inappropriate responses in a Go/No-go task. C_LIO_LIMice correct errors as they learn. C_LIO_LIDecision revisions are shaped by stimulus complexity. C_LIO_LIOptogenetic activation of the olfactory bulb inhibitory interneurons modulates decision revisions. C_LI